Various gene expression promoters, such as CMV promoters and CAG promoters, have been developed to increase gene expression efficiency (patent documents 1 to 4). However, the use of these conventional techniques causes daily problems in the field of biotechnology, such as situations in which almost no gene expression takes place or the amount of the thus-expressed protein is extremely low, depending on cell type or gene type. Furthermore, these problems serve as significant barriers to the development of medical science in which gene expression is used for diagnosis or treatment.
Patent document 1 JP Patent Publication No. 2814433
Patent document 2 JP Patent Publication No. 2814434
Patent document 3 U.S. Pat. No. 5,168,062
Patent document 4 U.S. Pat. No. 5,385,839